Sepsis and Chikungunya

Amesh A. Adalja, MD, FACP, FACEP, FIDSA, April 15, 2016

One of the common ways that many infectious diseases cause morbidity and mortality is the sepsis cascade. Virtually all microbes, in the correct context, can trigger this cascade, with varying degrees of likelihood. This includes the Aedes mosquito–transmitted virus chikungunya. While many clinicians are aware of chikungunya’s spread and its cardinal symptoms, fewer are probably aware of its propensity to cause sepsis and septic shock, as recently documented in a study published in Emerging Infectious Diseases.

Guadeloupe Outbreak

Related to the recent appearance of the autochthonous spread of chikungunya in the Western hemisphere, the island of Guadeloupe experienced a large outbreak in which an estimated 40% of the population was infected. Of those, 450 PCR-positive patients were admitted to the University Hospital of Pointe-à-Pitre and were the focus of the study, which described severe manifestations of the infection.

The 450 patients were 241 children, 99 pregnant women, and 110 nonpregnant adults. The authors divided chikungunya cases into 3 forms: the common form, which consisted of fevers and arthralgias; an atypical form, in which at least 1 organ system was involved; and a severe form, in which at least 1 organ system was in failure or where an ICU admission occurred.

In the group of nonpregnant adults, 34 had common forms, 34 atypical, and 42 severe. Characteristics of those with common and atypical forms were not disparate, so severe and nonsevere cases were compared. Patients with the severe form were, interestingly, neither older nor did they have more comorbid conditions. Rates of classic presentations of chikungunya in patients with severe and nonsevere forms were also similar. Patients with the severe form were more likely to exhibit leukocytosis, neutrophilia, and elevated lactate dehydrogenase (LDH) levels at baseline and at 1 week.

Severe Sepsis

The earlier classification of sepsis (which has since been revised) included a category of severe sepsis in which at least 1 organ system is in a state of dysfunction. Of the severe patients, 60% met the criteria for severe sepsis. The mortality rate in this subgroup was 48%, 16-fold higher than in those without the condition. No additional bacterial isolates were found in these patients.

Chikungunya Is a Severe Illness

Despite the fact that most people have mild courses of illness with chikungunya, it is well known that this virus can have severe manifestations in certain patients. Central nervous system complications have been well described. The linkage of sepsis to chikungunya is an important finding that reinforces the fact that, in any given host, a microbe can have varied manifestations and a broad spectrum of illness resulting from the unique characteristics of the host immune system and its interaction with the microbe. This fact is exemplified in the severe patients who exhibited leukocytosis, neutrophilia, and elevated LDH, all signs of immune activation.

While the world readies for battle with Zika, another virus spread by Aedes mosquitoes, this article is a reminder that chikungunya—which debuted in the Western hemisphere in 2013 in a manner much like Zika—remains a formidable foe with a real capacity to cause severe disease.